The Bobbsey Twins at Cedar Camp was published in 1921 and follows the family on an extended camping vacation at a lakeside lumber camp belonging to family friends. The setting allows the series to mix its standard outdoor-adventure formula with the specific details of early-twentieth-century North American lumber operations: the logging trails, the camp dining hall, the various pieces of timber-cutting machinery, the men who worked the camps for months at a time.
The central plotline involves a small-scale mystery about logs going missing from the camp’s daily output. Bert investigates and discovers that a neighboring camp has been quietly tagging Cedar Camp’s timber as their own and floating it downriver to their own mill. The resolution is handled by the Bobbsey adults negotiating with the rival camp’s owner rather than by any kind of confrontation. Flossie and Freddie spend most of the book covered in pine sap. A solid representative of the working-setting Bobbsey volumes.